I would suggest finding out what is involved with removing the transmission pan on your particular car as a first step.

More often than not the dipstick tube does not give up its marriage to the pan willingly. The big hex is a fixed counter hold to the pan and the smaller hex is what turns.... sometimes. If it doesn't turn you will need to remove the bellhousing bolt that secures the tube. Some people have reported simply cutting the dipstick tube and then reconnecting it with a piece of hose and a couple of clamps, but I have not resorted to that procedure, yet...

I find it very difficult to attach the cable onto the piece in the transmission. You have to turn the spring loaded piece and hold it while inserting the end of the cable much in the same fashion as the other end attaches to the throttle spool. No suggestions from me on how to make that easier but a boatload of patience would be helpful.

Good luck,
Randy